Electrical phase indicating apparatus



* 21 194?- J.H.BOLLMAN Em 2, 29,

ELIEIGTRICAL PHASE INDICATING APPARATUS Filed 001',- 4, 1944 .JH BOLLMAN wl/L/vrons- JG KREER) JR ATTORNEY trical quantities, means for translating the phase dividual tubes 35 ,and 36 are R.-C. networks 31 series with the secondary winding of a trans- The transformer 0Ci gned that voltformer 29. This transformer has its primary-50 s Produced across ts individual secondary winding connected by leads 30, 30 to leads H, H. windings are equalin The output circuit of amplifier 28 embodies the Theivoltage across R.-C. network 59 is PIOP mess ELECTRICAL PHASE nsnroarmo APPARATUS Application October 4, 1944, sci-in No. 557,178

- 3 Claims. (!.172-245) This invention relates to apparatus for indicatprimary winding of a transformer d2 whose secing the phase relationship between two alternatondary winding is positioned in the input circuit ing quantities. of balanced rectifier 3d. Leads 33, 33 joined to The general object of the invention is to indileads i5, it at points intermediate the input of cate continuously the phase angle between two 5 modulator it and the secondary windings of electrical quantities in a manner which substantransformer ti, connect the leads iii, 05 to the tially obviates the effect of the amplitudes of such primary winding of transformer 43 whose sectwo quantities. ondary winding is embodied in the input circuit In a specific embodiment, the present invenof rectifier M. This rectifier comprises diode on mpr wo independent sources of electo tubes 35 and 3B. In the output circuits of the indifference between such two quantities into a diand 38, respectively An indicator ll is connected riot cluzrent voltagle whose mragnigude is tIIJI'OpOI- across the output terminals 39, M of rectifier 3t. Ona 0 Sin W ere a S e p ase i erence The circuit shown in the drawing operates to zetweenltthei twitihquanftitiesi, and independent 1o: prildlice across 1tlllle terminals 39 and to a rectified 6 p 1 11 8S O a ans reSDons ve v0 t ge wh ch s a magnitude proportional to such direct current voltage for continuously indisine, where a is the phase angle between the atin the phase angle betw n t tw q t signal voltages v1 and V2 and which is independtie sfh in ti m b an d tood i cut of the amplililzudes g1 both these voltages, in

e ven on w e rea y un ers mm amanner that wi now e explained. the following description taken together with the t t b u d that th signal voltage V =V drawin the sin e fi ure f w c i ust at s a sin (pt); the signal voltage VZ=V2 sin (pt+a), 4 speRcgic eimbgdigilencilar of the inventilotn. i where a is the phase angle between the two sige 0 e aWmg. as 119115111185 011 nal voltages V]. and V2; the carrier voltage V11 line 8 transmits a signal voltage V1 and a signal (input to modulator l0)=Vu sin (Qt); and the transmission line 9 transmits a signal voltage V2. ar ier voltage V1 (in ut to the modulator Th input circuit of modulator Ill is connected it) =Vl1 sin (Qt+0), where 0 is the phase differin till? 1116 B a d i corrgspondmg 611118 g t :2 once established between thecarrier voltages V11 w ose opposi e en 5 re 00111180 8 0 e and V12 in a manner to be explained later, the output circuit of phase shifter l2. The inp t voltage V12 being identical in phase. and magitude 1131117 tlf h ph se1 tshifterfls con i z g 1?! ql l r l g with fig; voltage excep[t(as hQergnaftervpoirlifted 0 carrier vo age 0 prese ec e e c on n, 1 sin p and a=' 2 The input circuit of modulator Mis connected sin [(p Q)t+a-0] H n to the line 9 and corresponding ends of leads I5, V [5 whose opposite ends are alsotjoined to the out- V V =K V 5111 put circuit of the phase shifter l2. This phase 1 8+ 7 2 ;t m p )t]) shifter serves to establish initially a 90-degree phase diflerence between the carrier voltage por- V Sm [Ha-Q) t] tions transmitted on the leads H, II and 65, I5. 5 sin p Q The output circuits of modulators l0 and Id are 40 connected via transformers i and 8, respectively, Thus, the tub-e rectilfies the put 1illoltage V17 to the input circuit of a balanced rectifier i6 which comprises the tage across t e second comprising individual diode tubes i1 and I8. In My winding of transformer, 8 plus the Voltage the output circuits of the tubes i1 and I8 are disacross the upper Secondary ding of transformposed networks {9 and 20, respectively er l. The tube l5 rectifles the input voltage Leads 25, 25 connectoutput terminals 2| and 22 which cvmprlses the voltage across the 5600M- of the rectifier is across a capacilior 27 in the ary winding of transformer 8 minus the voltage put circuit of a variableelectronic tube 28, in across l r Secondary winding of transformprimary winding of transformer 3i which intional to the peak of the effective input voltage eludes two coupled secondary windings each of 1 r t fi d by tu e W. which/rectified voltage which is interposed in series in one of the leads {3 it, is. Leads s2, s2 connect leads ii, to the VIPKI a) The voltage across the R.-C. network 20 is proportional to the peak of the efiective input voltage V18 rectified by the tube I 8 which rectified voltage V3u=K V V -i V11-2V1"; 008 ((1-9) As the R..-C. networks 19 and 20 are connected in opposition in the output circuits of the respective tubes l1 and IS, the rectified voltage V15 effective across terminals 2| and 22 and supplied over leads 25, 25 to capacitor 21 is the difierence between the rectified voltage V111 and V20. Thus,

( V 5 z cos (a (1) Also, let it be assumed that the parameters oi thetube 28 and the circuit associated therewith are so chosen that the gain or tube 28 is no, that is, the voltage V11 (across secondary windings of transformer 3| =noV11, where the rectified voltage V2s=0, and the gain of tube 28 changes proportionally to variations of the rectified voltage V15 with reference to zero. Accordingly, the volt- V1s=V12+Va1 =V12+(no+n1Va5) V11 (2) The carrier voltages V11 and V15 may be initially selected by proper adjustment of the phase shifter l2 so that a phase quadrature relationship exists therebetween. Now, considering the condition Vz=0 1 V=V12 sin (Qt-H1) +noV11 sin (Qt) in which obviously the sign must be used. Substituting these values in Equation 2,

o u Bill (Q 1 2t 1i Bin (Q0 1 n V tan a (3) Equation 3 may be solved for V215 and then the factor (n1) chosen so that the voltage V15 is made verynearly equal to zero. In such case, cos (11-0) in Equation 1 is also made very nearly equal to zero since K1, V1 and V2 individually have values other than zero; and therefore under the equilibrium condition very nearly )r 1r 9% G (3a) By a similar analysis, it can be demonstrated that 2K V V V41 (across terminals 39, 40) Q-f i-Z cos 6:

2K V V 8111 a p 1/ Vu=+ Via As V15=V11. very nearly, then V41=K1V11 sin a (4) Referring to Equation 1 and assuming then I 2K1V V, 5 V15 B111 0 The factor (n1) tends to vary the amount of current in the output circuit of the tube 28 with reference to the amount of current prevailing therein under the equilibrium condition and thereby the phase of the carrier voltage V15. As the-phase of carrier voltage V15 differs initially from the phase of carrier voltage V11 by 90 degrees, the efiect of the factor (111) is to vary the phase of carrier voltage V15, with reference to the 90 degrees, in aproportional manner. Hence, the variation of the phase of carrier voltage V15 with reference to 90 degrees is proportional to the voltage (V15). As above pointed out, the gain (m) of tube 28, or the voltage V25, tends to reduce the factor cos (11:0) in Equation 1 to every small quantity. This tends to establish a phase relationship between V11 and V15 such as to set up a quadrature relationship between the voltages V: and Va, and hence makes the phase relationship between the carrier voltages V11 and V15 differ from' by an amount a as indicated in Equation 3a;

Referring to Equation 4, the factors K1 and V11 are design constants of the circuit. Hence, the

voltage V41 depends only upon these constants and sin a where a is the phase difference between the two signal voltages V1 and V2, and is independent of their amplitudes. The rectified voltage V41 produces appropriate phase readings on indicator ii. This indicator is calibrated to produce a zero reading when sin a is zero, that is, when phase quadrature substantially occurs between the carrier voltages V11 and V15.

* It will beunderstood that the variable i tube 28 is illustrative of one type of device capable of utilizing rectified voltage for accomplishing phase control, and other devices equally suitable for the same purpose will occur to those skilled in the art.

What is claimed is:

1. A phase detecting circuit comprising two modulating devices, means for producing two carrier voltages in phase quadrature, circuit means for applying each of two signal voltages to the input circuit of a respective one of said moduvoltage, means for utilizing such rectified voltage to control the phase of the translated portion of one of said two carrier voltages with reference to 90 degrees, and further differential means for detecting the phase difference between the two translated'portions of the two carrier voltages, with reference to the initial QO-degree phase difference therebetween, to obtain an indication of the phase difference between said two signal voltages.

3. In a system for measuring the phase difference between two signal voltages, two independent sources of signal voltage, means for producing two carrier voltages differing in phase by 90 degrees, means for translating each signal voltage and a first portion of each carrier voltage into a a further voltage, 'difierential means for detecting said further voltages to produce a-rectified voltage, means for utilizing such rectified voltage and a second portion of one carrier voltage to control thephase of the translated first portion lating devices, additional circuit means for 2119- plying each of said two carrier voltages to the input circuit of a respective one of said modulating devices, differential detecting means con,- nected to the output circuits of both said modulating devices for producing a rectified voltage, phase changing means controlled by said firstmentioned rectified-voltage to vary the relative phases of the carrier voltages applied to said modulating devices, further differential detecting means connected to said additional circuit means for producing a second rectified voltage, and an indicator connected to said further detecting means and responsive to the second rectified voltage.

2. In combination in a circuit for indicating the phase difference between two signal voltages, two discrete sources of signal voltage whose phase diflerence is to be indicated, means for producing two carrier voltages one of which differs in phase from the other by 90 degrees, means for translating said two signal voltages and one portion of each of said two carrier voltages into two further voltages, differential means for detecting said two further voltages to produce a rectified of the second carrier voltage, further differential means for utilizing'a third portion of the one carrier voltage and a further portion of the translated first portion of the second carrier voltage to produce a, rectified voltage proportional to sin a, where a is the phase difference between the two signal voltages, and independent of the amplitudes of the two signal voltages, and means responsive to the last rectified voltage for indicating the phase difierence between the two signal voltages.

JOHN H. BOLLMAN. JOHN G. KREER, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,333,322 Levy Nov. 2, 1943 2,209,064 Nyquist July 23, 1940 2,225,348 Mikelson Dec. '17, 1940 2,405,073 Troell July 30, 1946 

